MSAA differences in GLFW and FBO

I’m developing an application which makes small video with a 3D animation scene. It has two modes:

  • first (“View”) - animation is showing in GLFW window.
  • second (“Create video”) - animation is saving to video file, rendering is performed via FBO.

I use MSAA (4x) for better looking:

  • in View mode - Glfw.WindowHint(Hint.Samples, 4);
  • in Create video mode I use FBO with multisampled (also 4x) Renderbuffer, downsampling it via glBlitFramebuffer.

And I found that resulting images are different! Please, tell me, how to make them same? Because image quality in GLFW is better than via FBO, maybe I missed something? I am a new in OpenGL, so maybe my question is stupid, sorry for that…
Left image is from View mode, right is from Create video mode.